In our electronic age, there is a continuing search to reduce the size of the instrumentation that can be used for electronic display of information to the user. The electronic display provides the user""s eyes with an image, which can be either real or virtual. A real image refers to an image which is observed directly by the unaided human eye, e.g., a photograph or an electronic display as provided by a computer monitor. The virtual image is an image which, if a viewing surface were positioned at the apparent location of the virtual image, no image would be observed on the viewing surface. The virtual image facilitates enhanced miniaturization since the size or location of the viewing surface no longer limits its display location.
Head mounted virtual image display systems are well known as illustrated by: Jachinowicz et al in U.S. Pat. No. 5,224,198; Tosaki in U.S. Pat. No. 5,712,649; and Taniguchi et al in U.S. Pat. No. 5,790,284. In the classic head mounted display systems, the light rays emitted by the liquid crystal display (LCD) screen are directed by a lens onto a beam splitter. The beam splitter when oriented toward the user""s eye enables the viewer to see the virtual image projected by the LCD
Hildeband et al in U.S. Pat. No. 5,625,372 teaches a compact virtual image display system in which he combines a virtual image display and an eye tracker into a compact unit with a light emitting diode (LED) ring 58 about an optic lens 26 and an liquid crystal display (LCD) with feed back controls. Unfortunately, his system is not susceptible to head mounted displays. Furness, III et al in U.S. Pat. No. 5,467,104 describe in FIG. 4 an eye tracking device with a charged couple device (CCD) array detector but not useful for head mounted displays.
There exists a serious need for a head mounted, virtual image display system that will cooperatively provide eye tracking of the sight direction whereby physically challenged people can interact with devices. The sight direction information is also needed to enhance local images displayed in head mounted devices, correct for some depth perception difficulties, enhanced psychological studies by noting eye reactions to virtual image displays and increased resolution at the gaze point of visual displays.
The first objective of the present invention is to provide the user with a head mounted display that has an integrated eye-tracking function.
The second object of this invention is to provide a head mounted optical display system wherein the optical system provides a means to display the virtual image.
The third objective of this invention is to provide a head mounted optical display system with multiple infrared-emitting diodes positioned symmetrically around the optical system.
The fourth objective of this invention is to provide a head mounted, virtual image eye-tracking display system wherein the reflected infrared radiation is optically focused on a CCD sensor after reflection from the eye.
The primary embodiment of this invention is exemplified by a head mounted optical eye tracking apparatus for a user comprising in combination: an optical system means for displaying virtual images to a user""s eye; and, means for tracking at least one, preferably both, of the user""s eyes to determine sight direction.
The method of the invention includes the critical steps of displaying a virtual image to a user""s eye, positioning a multiple infrared radiation eye-tracking display means peripherally of one imaging lens and imaging the user""s eye to compute sight direction by means invisible to the user.
Further objects and advantages of this invention will be apparent from the following detailed description of a presently preferred embodiment, which is illustrated schematically in the accompanying drawings.